The Pharmacokinefics, Bioavailability, and Metabolism Core will provide the Botanical Research Center with validated analytical methods based on tandem mass spectrometry and isotope dilufion to idenfify and quantify the various botanical estrogens and potenfial metabolites in experimental pre-clinical models from Research Projects 2 and 3. The internal exposure data collected from plasma and specific target fissues, including mammary gland, uterus, and brain regions, will be used to determine appropriate dosing and possible differences in bioavailability for whole botanicals vs. purified acfive ingredients. These tools will provide a comprehensive evaluation of pharmacokinetics and metabolism to be included in all assessments of botanical estrogens in the various organ systems.